﻿#include "md5.h"

/* F, G and H are basic MD5 functions: selection, majority, parity */
#define F(x, y, z) (((x) & (y)) | ((~x) & (z)))
#define G(x, y, z) (((x) & (z)) | ((y) & (~z)))
#define H(x, y, z) ((x) ^ (y) ^ (z))
#define I(x, y, z) ((y) ^ ((x) | (~z))) 

/* ROTATE_LEFT rotates x left n bits */
#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))

/* FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4 */
/* Rotation is separate from addition to prevent recomputation */
#define FF(a, b, c, d, x, s, ac) \
  {(a) += F ((b), (c), (d)) + (x) + (ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
  }
#define GG(a, b, c, d, x, s, ac) \
  {(a) += G ((b), (c), (d)) + (x) + (ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
  }
#define HH(a, b, c, d, x, s, ac) \
  {(a) += H ((b), (c), (d)) + (x) + (ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
  }
#define II(a, b, c, d, x, s, ac) \
  {(a) += I ((b), (c), (d)) + (x) + (ac); \
  (a) = ROTATE_LEFT ((a), (s)); \
  (a) += (b); \
  }

namespace nsshare
{
namespace algorithm
{

MD5Provider::MD5Provider()
{
    Reset();
}

void MD5Provider::Reset()
{
    context_.i[0] = context_.i[1] = 0;
    /* Load magic initialization constants.*/
    context_.buf[0] = 0x67452301;
    context_.buf[1] = 0xefcdab89;
    context_.buf[2] = 0x98badcfe;
    context_.buf[3] = 0x10325476;
}

void MD5Provider::Update(const void * data, size_t size)
{
    uint32_t in[16];
    uint32_t i, ii;
    uint32_t mdi;

    /* compute number of bytes mod 64 */
    mdi = (context_.i[0] >> 3) & 0x3F;

    /* update number of bits */
    if ((context_.i[0] + (size << 3)) < context_.i[0])
        context_.i[1]++;

    context_.i[0] += (size << 3);
    context_.i[1] += (size >> 29);

    auto buffer = reinterpret_cast<const uint8_t *>(data);

    if(size == 0 || data == 0)
        return;

    while (size--) 
    {
        /* add new character to buffer, increment mdi */
        context_.in[mdi++] = *buffer++;

        /* transform if necessary */
        if (mdi == 0x40) 
        {
            for (i = 0, ii = 0; i < 16; i++, ii += 4)
            {
                in[i] = ((context_.in[ii+3]) << 24) |
                    ((context_.in[ii+2]) << 16) |
                    ((context_.in[ii+1]) << 8)  |
                    (context_.in[ii]);
            }
            Transform (context_.buf, in);
            mdi = 0;
        }
    }
}

void MD5Provider::Final(Hash & hash)
{
    uint32_t in[16];
    uint32_t i, ii;
    uint32_t padLen;
    int mdi;

    const static uint8_t padding[64] = 
    {
        0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    };

    /* save number of bits */
    in[14] = context_.i[0];
    in[15] = context_.i[1];

    /* compute number of bytes mod 64 */
    mdi = (context_.i[0] >> 3) & 0x3F;

    /* pad out to 56 mod 64 */
    padLen = (mdi < 56) ? (56 - mdi) : (120 - mdi);
    Update (padding, padLen);

    /* append length in bits and transform */
    for (i = 0, ii = 0; i < 14; i++, ii += 4)
        in[i] = ((context_.in[ii+3]) << 24) |
        ((context_.in[ii+2]) << 16) |
        ((context_.in[ii+1]) << 8) |
        (context_.in[ii]);
    Transform (context_.buf, in);

    /* store buffer in digest */
    for (i = 0, ii = 0; i < 4; i++, ii += 4) 
    {
        context_.digest[ii] = context_.buf[i] & 0xFF;
        context_.digest[ii+1] = (context_.buf[i] >> 8) & 0xFF;
        context_.digest[ii+2] = (context_.buf[i] >> 16) & 0xFF;
        context_.digest[ii+3] = (context_.buf[i] >> 24) & 0xFF;
    }

    hash = Hash(context_.digest, sizeof(context_.digest));
}

void MD5Provider::Transform(uint32_t * buf, uint32_t * in)
{
    uint32_t a = buf[0], b = buf[1], c = buf[2], d = buf[3];

    /* Round 1 */
#define S11 7
#define S12 12
#define S13 17
#define S14 22
    FF ( a, b, c, d, in[ 0], S11, 3614090360); /* 1 */
    FF ( d, a, b, c, in[ 1], S12, 3905402710); /* 2 */
    FF ( c, d, a, b, in[ 2], S13,  606105819); /* 3 */
    FF ( b, c, d, a, in[ 3], S14, 3250441966); /* 4 */
    FF ( a, b, c, d, in[ 4], S11, 4118548399); /* 5 */
    FF ( d, a, b, c, in[ 5], S12, 1200080426); /* 6 */
    FF ( c, d, a, b, in[ 6], S13, 2821735955); /* 7 */
    FF ( b, c, d, a, in[ 7], S14, 4249261313); /* 8 */
    FF ( a, b, c, d, in[ 8], S11, 1770035416); /* 9 */
    FF ( d, a, b, c, in[ 9], S12, 2336552879); /* 10 */
    FF ( c, d, a, b, in[10], S13, 4294925233); /* 11 */
    FF ( b, c, d, a, in[11], S14, 2304563134); /* 12 */
    FF ( a, b, c, d, in[12], S11, 1804603682); /* 13 */
    FF ( d, a, b, c, in[13], S12, 4254626195); /* 14 */
    FF ( c, d, a, b, in[14], S13, 2792965006); /* 15 */
    FF ( b, c, d, a, in[15], S14, 1236535329); /* 16 */

    /* Round 2 */
#define S21 5
#define S22 9
#define S23 14
#define S24 20
    GG ( a, b, c, d, in[ 1], S21, 4129170786); /* 17 */
    GG ( d, a, b, c, in[ 6], S22, 3225465664); /* 18 */
    GG ( c, d, a, b, in[11], S23,  643717713); /* 19 */
    GG ( b, c, d, a, in[ 0], S24, 3921069994); /* 20 */
    GG ( a, b, c, d, in[ 5], S21, 3593408605); /* 21 */
    GG ( d, a, b, c, in[10], S22,   38016083); /* 22 */
    GG ( c, d, a, b, in[15], S23, 3634488961); /* 23 */
    GG ( b, c, d, a, in[ 4], S24, 3889429448); /* 24 */
    GG ( a, b, c, d, in[ 9], S21,  568446438); /* 25 */
    GG ( d, a, b, c, in[14], S22, 3275163606); /* 26 */
    GG ( c, d, a, b, in[ 3], S23, 4107603335); /* 27 */
    GG ( b, c, d, a, in[ 8], S24, 1163531501); /* 28 */
    GG ( a, b, c, d, in[13], S21, 2850285829); /* 29 */
    GG ( d, a, b, c, in[ 2], S22, 4243563512); /* 30 */
    GG ( c, d, a, b, in[ 7], S23, 1735328473); /* 31 */
    GG ( b, c, d, a, in[12], S24, 2368359562); /* 32 */

    /* Round 3 */
#define S31 4
#define S32 11
#define S33 16
#define S34 23
    HH ( a, b, c, d, in[ 5], S31, 4294588738); /* 33 */
    HH ( d, a, b, c, in[ 8], S32, 2272392833); /* 34 */
    HH ( c, d, a, b, in[11], S33, 1839030562); /* 35 */
    HH ( b, c, d, a, in[14], S34, 4259657740); /* 36 */
    HH ( a, b, c, d, in[ 1], S31, 2763975236); /* 37 */
    HH ( d, a, b, c, in[ 4], S32, 1272893353); /* 38 */
    HH ( c, d, a, b, in[ 7], S33, 4139469664); /* 39 */
    HH ( b, c, d, a, in[10], S34, 3200236656); /* 40 */
    HH ( a, b, c, d, in[13], S31,  681279174); /* 41 */
    HH ( d, a, b, c, in[ 0], S32, 3936430074); /* 42 */
    HH ( c, d, a, b, in[ 3], S33, 3572445317); /* 43 */
    HH ( b, c, d, a, in[ 6], S34,   76029189); /* 44 */
    HH ( a, b, c, d, in[ 9], S31, 3654602809); /* 45 */
    HH ( d, a, b, c, in[12], S32, 3873151461); /* 46 */
    HH ( c, d, a, b, in[15], S33,  530742520); /* 47 */
    HH ( b, c, d, a, in[ 2], S34, 3299628645); /* 48 */

    /* Round 4 */
#define S41 6
#define S42 10
#define S43 15
#define S44 21
    II ( a, b, c, d, in[ 0], S41, 4096336452); /* 49 */
    II ( d, a, b, c, in[ 7], S42, 1126891415); /* 50 */
    II ( c, d, a, b, in[14], S43, 2878612391); /* 51 */
    II ( b, c, d, a, in[ 5], S44, 4237533241); /* 52 */
    II ( a, b, c, d, in[12], S41, 1700485571); /* 53 */
    II ( d, a, b, c, in[ 3], S42, 2399980690); /* 54 */
    II ( c, d, a, b, in[10], S43, 4293915773); /* 55 */
    II ( b, c, d, a, in[ 1], S44, 2240044497); /* 56 */
    II ( a, b, c, d, in[ 8], S41, 1873313359); /* 57 */
    II ( d, a, b, c, in[15], S42, 4264355552); /* 58 */
    II ( c, d, a, b, in[ 6], S43, 2734768916); /* 59 */
    II ( b, c, d, a, in[13], S44, 1309151649); /* 60 */
    II ( a, b, c, d, in[ 4], S41, 4149444226); /* 61 */
    II ( d, a, b, c, in[11], S42, 3174756917); /* 62 */
    II ( c, d, a, b, in[ 2], S43,  718787259); /* 63 */
    II ( b, c, d, a, in[ 9], S44, 3951481745); /* 64 */

    buf[0] += a;
    buf[1] += b;
    buf[2] += c;
    buf[3] += d;
}

}
}
